The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs. Such scaling down has also increased the complexity of processing and manufacturing ICs. For these technological advancements to be realized, similar developments in IC processing and manufacturing are needed.
For example, extreme ultraviolet (EUV) lithography has been utilized to support critical dimension (CD) requirements of smaller devices. EUV lithography employs scanners using radiation in the EUV region, having a wavelength of about 1-100 nm. Currently, EUV lithography has a limited production capacity, partly because typical EUV sources cannot provide large enough radiation powers. For example, a typical EUV source can only generate about 80 W radiation powers, while it needs about 250 W to satisfy volume production. To overcome this issue, some efforts have been spent on increasing EUV resist sensitivity. However, as resist sensitivity increases, the line edge roughness (LER) and line width roughness (LWR) of the developed resist patterns also increase. This leads to decreased critical dimension uniformity (CDU) and degraded circuit performance.
Accordingly, while existing EUV lithography methods are generally adequate for their intended purposes, they are not entirely satisfactory in all respects.